There are some things that change as you get older. The traits you desire in a partner, for example, and your idea of what constitutes a night out. But the fundamentals of fitness stay the same no matter how many birthday cakes you’ve consumed. What happens to your body as you age? Gradual decline in oestrogen, progesterone and growth hormone, especially after menopause. Muscle mass declines Bone density declines Recovery time increases Mobility decreases Balance declines Met